The present invention relates to a method and a device for the subjective determination of aberrations of higher order in an optical system, in particular in an eye.
In order to improve the quality of optical systems such as imaging systems and laser irradiation, optical wavefronts of these systems are analysed. In the article “Objective measurement of wave alternations of the human eye with the use of a Hartmann-Shack wave front sensor” by Liang et al, Optical Society of America 1994, p. 1949 ff., it is described how, with Shack-Hartmann sensors, aberrations of higher order can be recorded and evaluated in the form of Zernike coefficients of the various orders.
This objective determination of the Zernike coefficients results in an improvement in quality of the system. However, this objective improvement in quality displays differences from the subjectively evaluated visual power of this optical system.
This fact has been taken into account for the conventional spherocylindrical correction of refractive errors of the human eye in that the ophthalmologist objectively establishes the correction values by means of refractometers and then, in order to provide the subjective fine adjustment for the patient, determines the final data by means of test spectacles or a phoropter and a reading chart. For higher aberrations (starting from the 3rd order), these subjective tests end merely in a straight decision that the correction does or does not achieve certain effects. However, a subjective fine adjustment is not possible.
Beyond the normal spherical and cylindrical correction of aberrations, in order to correct higher aberrations as well, adaptive lenses can be used in theory which operate as deformable mirrors in reflection or liquid crystal lenses in transmission. Despite intense efforts, however, these adaptive lenses cannot yet be used industrially due to their sensitivity.